The present invention is directed to a device designed for the sidewise shifting of a tool on a rotary shaft in a slotting station located within a machine used for converting thick, solid or corrugated board into boxes. For a better understanding of the invention, it should be added that as a sheet is transferred along a given direction, the station along this direction of transfer will, first, accomplish a creasing operation to prepare parallel lines for ultimate folding and, then, provide a slotting operation on both the upstream and downstream edges of the sheet or plate, which edges are normally situated on the extensions of the previously imprinted creasing lines. The slots will define the future box flaps. In order to insure a regular accomplishment of this process, a driving operation is frequently interposed or sandwiched between the two above-mentioned stations performing the two above-mentioned operations.
For the purposes of this operation, the plate-like or sheet-like workpieces travel through pairs of circular tools consisting each of an active tool and a counterpart fitted on an upper and lower horizontal shaft arranged perpendicular to the travelling direction of the workpieces. The station, thus, usually includes three pairs of vertical shafts, one for the creasing at the inlet, a center driving section and a slotting section at the outlet of the station. Moreover, this station will include a mechanism enabling the sidewise shifting of the assembly of the three tool pairs situated along a common line that extends parallel to the travelling direction of the workpiece, which mechanism is designed to allow the holding of the slotting tools axially aligned with the creasing tools during the setting of the size of the boxes to be produced.
Each of these mechanisms essentially consist of a master plate for the three upper tools of the three pairs of tools and a master plate for the lower three tools of the three pairs of tools. These plates are provided on their periphery with means for guiding the sidewise positioning of the tools situated on their respective shafts. Such guide means can, for example, include an arch-like or arcuate slot with a fork effect which engages in a crosswise groove of the circular tool, which groove enables the tool to be able to turn freely by means of the driving shaft. Another guiding means consists of a broader arch-like slot completed with dogs or sliding shoes which both engage in the crosswise groove of the tool. Other ways of realization are also possible, for example the use of a salient wearing disk turning with the tool and held between two wearing sliding shoes situated on either side of the plate.
Every master plate is held vertically in the travelling direction of the workpieces by at least two shafts, one of which is a smooth guiding shaft passing through the fork of the plate which is completed by an upper and lower guiding box being in contact with this one shaft. The second shaft is a threaded shaft passing through a ball-nut permanently fitted on the master plate. When, owing to an electric motor, the threaded shaft acting on the ball-nut of the plate is rotated, the plate will be shifted sidewise, i.e., to the right or the left side, along the axis of the threaded shaft with the amount of shifting being perfectly vertical or perpendicular to the travelling direction of the workpieces. This plate can, then, simultaneously move the upper three tools, which will remain along a common line. A similar lower device will move the three lower counterpart tools.
In a slotting station comprising six parallel rows of tools, it is evident that the upper device for setting the position of the tools requires at least on common guiding shaft and three threaded shafts for setting the position of the tools if the blanks are symmetrical with regard to the median axis of the station. If the blanks are not symmetrical, then six individual shafts, i.e., three from each side, are required. The lower device will require an identical number of shafts.
It has further proven useful to shift sidewise over a short distance the creasing tool with regard to the slotting tool in such a way that the future fold appears a little closer to the one flap than to the other. In fact, during the folding operation of a box, a movement occurs when the first flap is to be folded inward in between the three others, which are still in a vertical position. In this case, if the folds are exactly centered with regard to the slots, the operation becomes difficult when just one of the adjacent flaps is slightly offset. On the contrary, if the fold is to happen exactly on the extension of the adjacent flap edge, the creasing action, being thereby effectuated on the extension of a side of the slot, the width of this same slot will then create, during the folding operation, a security margin on either side.
A first solution would consist in providing that only the upper part of every triple tool arrangement belonging to the same line, a first device for positioning only the creasing tool, as well as a second device for positioning the slotting tool and a driving tool would be provided. This solution might involve the doubling of the number of guiding shafts and threaded shafts bringing about a greater weight for the station and, thus, increasing the cost with a slight correction as compared to the initial shifts.
The presently used solution consists in dismantling the active part of the creasing tool from the body fitted on the shaft, and in fitting it again by laterally superimposing one or several shims having the shape of the crosswise disk with standard thickness. This solution would, however, involve a very long setting-up time when changing production from one box type to another. In fact, after every test run, the operator would need to dismantle the appropriate tool for changing the shims and then to continue a test run until the final results proved satisfactory.